In addition, the investigators will collect stool samples to at 0 and 7 days after delivery at of the bOPV. The stool samples would be collected from the field and transported to the National Institute of Health (NIH), Pakistan and processed according to the standard protocol used in the global polio laboratory network, including poliovirus isolation, ITD and sequencing. Non-polio enterovirus (NPEV) will be isolated but not characterized. A transport mechanism is well established which brings the stool and other biological samples from Hala/Matiari field site to the Aga Khan University on a daily basis, where the samples will be stored until shipment to the NIH (a WHO Regional Polio Network Laboratory) in Islamabad.